Spin polarization and π-phase state of the Josephson contact: Critical current of mesoscopic SFIFS and SFIS junctions

Elena Koshina; Vladimir Krivoruchko

doi:10.1103/PhysRevB.63.224515

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Spin polarization and π-phase state of the Josephson contact: Critical current of mesoscopic SFIFS and SFIS junctions

Elena Koshina, Vladimir Krivoruchko

DOI 10.1103/PhysRevB.63.224515 · Physical Review B

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Abstract

On the basis of a microscopic proximity effect model, the critical current of superconductor/ferromagnet/insulator/ferromagnet/superconductor (SFIFS) and superconductor/ferromagnet/insulator/superconductor Josephson junctions have been calculated. Both metals, a superconductor (S) and a ferromagnet (F), are supposed to be in a “dirty” limit and the thickness of the F layer is assumed to be small compared to its coherence length. It is shown that critical current in the SFIFS contact can reverse its sign and a crossover to the “π” state of the junction takes place even at a mesoscopic thickness of the F layer. We discuss, how by changing the SF sandwich parameters (a ferromagnetic exchange field, boundary transparency, and strength of proximity effect) the conditions for crossover from “0” to “π” phase shift across the contact are changed.